Extracting features with unclean canny detection

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I'll give this a shot! Thanks!

I don't have the original image at the moment but if you're wondering what it looks like, it's a very polished surface similar to this:

https://img1.etsystatic.com/042/0/6723474/il_340x270.621018835_tj4e.jpg

It would be similar to trying to box the raised portion in the middle of the button.

I gave the above a shot but I think my lines are too broken for it to work properly.

Contour before Hull: Click here After Hull (black): Click here

Is there a way to perhaps join lines that are close together? Perhaps with less broken lines I can get a better result? Or maybe you guys have other ideas. :)

Could you share the code you used? You are going to have to filter the points from the contours, I will see if I can give you some pointers.

It's quite messy to be honest. I have a whole bunch of other attempts inside that I commended out. But basically the breakdown is:

image >> Gaussian Blur (3,3) >> Canny >> Canny to Binary >> dilates and errodes to thicken lines >> findCountors

If I can somehow extend lines until 2 lines meet, I think I can get away with it.

There is no easy way to extend the lines that I know of, you will need to go through the points of the contours and perform the operation, below is something I just googled to do so. Filtering contours can be a messy task because you have to compare different contours points. My suggestion would be to play around for a better convex hull result.

for(size_t i=0; i<contours.size(); i++) { // use contours[i] for the current contour

for(size_t j=0; j<contours[i].size(); j++) {

//use contours[i][j] for current point

}}

What the data type for contours[i]? I tried int/double/float point = contours[i] but all failed. Error 4 error C2440: 'initializing' : cannot convert from 'std::vector<cv::Point,std::allocator<_Ty>>' to 'float'

contours is vector<vector<Point>>

contours[i] is vector<Point>

contours[i][j] is Point so to access the value you will need to use contours[i][j].x and contours[i][j].y